Methods for multi-wire routing and apparatus implementing same

ABSTRACT

A rectangular interlevel connector array (RICA) is defined in a semiconductor chip. To define the RICA, a virtual grid for interlevel connector placement is defined to include a first set of parallel virtual lines that extend across the layout in a first direction, and a second set of parallel virtual lines that extend across the layout in a second direction perpendicular to the first direction. A first plurality of interlevel connector structures are placed at respective gridpoints in the virtual grid to form a first RICA. The first plurality of interlevel connector structures of the first RICA are placed to collaboratively connect a first conductor channel in a first chip level with a second conductor channel in a second chip level. A second RICA can be interleaved with the first RICA to collaboratively connect third and fourth conductor channels that are respectively interleaved with the first and second conductor channels.

CLAIM OF PRIORITY

This application is a continuation application under 35 U.S.C. 120 ofprior U.S. application Ser. No. 14/298,206, filed Jun. 6, 2014, which isa continuation application under 35 U.S.C. 120 of prior U.S. applicationSer. No. 13/918,890, filed Jun. 14, 2013, issued as U.S. Pat. No.8,759,985, on Jun. 24, 2014, which is a continuation application under35 U.S.C. 120 of prior U.S. application Ser. No. 13/085,447, filed Apr.12, 2011, issued as U.S. Pat. No. 8,471,391, on Jun. 25, 2013, which isa divisional application under 35 U.S.C. 121 of prior U.S. applicationSer. No. 12/411,249, filed Mar. 25, 2009, issued as U.S. Pat. No.7,939,443, on May 10, 2011, which claims the priority benefit of U.S.Provisional Patent Application No. 61/040,129, filed Mar. 27, 2008. Thedisclosure of each above-identified application is incorporated hereinby reference in its entirety.

BACKGROUND

A push for higher performance and smaller die size drives thesemiconductor industry to reduce circuit chip area by approximately 50%every two years. The chip area reduction provides an economic benefitfor migrating to newer technologies. The 50% chip area reduction isachieved by reducing the feature sizes between 25% and 30%. Thereduction in feature size is enabled by improvements in manufacturingequipment and materials. For example, improvement in the lithographicprocess has enabled smaller feature sizes to be achieved, whileimprovement in chemical mechanical polishing (CMP) has in-part enabled ahigher number of interconnect layers.

In the evolution of lithography, as the minimum feature size approachedthe wavelength of the light source used to expose the feature shapes,unintended interactions occurred between neighboring features. Todayminimum feature sizes are approaching 32 nm (nanometers), while thewavelength of the light source used in the photolithography processremains at 193 nm. The difference between the minimum feature size andthe wavelength of light used in the photolithography process is definedas the lithographic gap. As the lithographic gap grows, the resolutioncapability of the lithographic process decreases.

An interference pattern occurs as each shape on the mask interacts withthe light. The interference patterns from neighboring shapes can createconstructive or destructive interference. In the case of constructiveinterference, unwanted shapes may be inadvertently created. In the caseof destructive interference, desired shapes may be inadvertentlyremoved. In either case, a particular shape is printed in a differentmanner than intended, possibly causing a device failure. Correctionmethodologies, such as optical proximity correction (OPC), attempt topredict the impact from neighboring shapes and modify the mask such thatthe printed shape is fabricated as desired. The quality of the lightinteraction prediction is declining as process geometries shrink and asthe light interactions become more complex.

In view of the foregoing, techniques are sought for managinglithographic gap issues as technology continues to progress towardsmaller semiconductor device features sizes.

SUMMARY

In one embodiment, a method is disclosed for defining a rectangularinterlevel connector array (RICA) in a semiconductor chip layout. Themethod includes an operation for defining a virtual grid for interlevelconnector placement. The virtual grid is defined by a first set ofparallel virtual lines that extend across the layout in a firstdirection and by a second set of parallel virtual lines that extendacross the layout in a second direction that is perpendicular to thefirst direction. Each intersection point between the first and secondsets of parallel virtual lines is a gridpoint in the virtual grid. Themethod also includes an operation for placing a first plurality ofinterlevel connector structures at respective gridpoints in the virtualgrid to form a first RICA. Neighboring interlevel connector structuresof the first RICA are spaced apart from each other by a first number ofgridpoints in the first direction and by a second number of gridpointsin the second direction. The first plurality of interlevel connectorstructures of the first RICA are placed to collaboratively connect afirst conductor channel in a first chip level with a second conductorchannel in a second chip level.

In another embodiment, a method is disclosed for wire routing in asemiconductor chip layout. The method includes an operation for defininga first conductor channel layout in a first chip level. The firstconductor channel layout includes a first plurality of parallel wirelayout shapes having a common electrical connectivity and oriented in afirst direction. The method also includes an operation for defining asecond conductor channel layout in a second chip level. The secondconductor channel layout includes a second plurality of parallel wirelayout shapes having a common electrical connectivity and oriented in asecond direction that is perpendicular to the first direction. The firstand second conductor channel layouts extend across each other within thechip layout at a crossing location. The method further includes anoperation for defining a first RICA layout at the crossing location toconnect the first conductor channel layout to the second conductorchannel layout. The first RICA layout includes a first plurality ofinterlevel connector layout shapes placed to collaboratively connect thewire layout shapes of the first conductor channel layout to the wirelayout shapes of the second conductor channel layout.

In another embodiment, a semiconductor chip is disclosed. The chipincludes a first conductor channel defined in a first chip level. Thefirst conductor channel includes a first plurality of parallel wireshaving a common electrical connectivity and oriented in a firstdirection. The chip also includes a second conductor channel defined ina second chip level. The second conductor channel includes a secondplurality of parallel wires having a common electrical connectivity andoriented in a second direction that is perpendicular to the firstdirection. The first and second conductor channels extend across eachother within the chip at a crossing location. The chip further includesa first RICA defined at the crossing location to connect the firstconductor channel to the second conductor channel. The first RICAincludes a first plurality of interlevel connectors placed tocollaboratively connect the wires of the first conductor channel to thewires of the second conductor channel.

In another embodiment, a layout of a semiconductor chip is disclosed.The layout includes a first conductor channel defined in a first chiplevel. The first conductor channel includes a first plurality ofparallel wire layout shapes having a common electrical connectivity andoriented in a first direction. The layout also includes a secondconductor channel defined in a second chip level. The second conductorchannel includes a second plurality of parallel wire layout shapeshaving a common electrical connectivity and oriented in a seconddirection that is perpendicular to the first direction. The first andsecond conductor channels extend across each other within the chip at acrossing location. The layout also includes a first RICA defined at thecrossing location to connect the first conductor channel to the secondconductor channel. The first RICA includes a first plurality ofinterlevel connector layout shapes placed to collaboratively connect thewire layout shapes of the first conductor channel to the wire layoutshapes of the second conductor channel.

Other aspects and advantages of the invention will become more apparentfrom the following detailed description, taken in conjunction with theaccompanying drawings, illustrating by way of example the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an illustration showing placement of wires and interlevelconnectors, in accordance with one embodiment of the present invention;

FIG. 1B shows an example layout in which a horizontally oriented virtualgrate of an interlevel connector placement virtual grid allows forplacement of interlevel connectors on adjacent virtual lines, inaccordance with one embodiment of the present invention;

FIG. 1C shows an example layout in which an interlevel connectorplacement virtual grid allows for placement of interlevel connectors onadjacent virtual lines in both the horizontal and vertical directions,in accordance with one embodiment of the present invention;

FIG. 2A shows an example layout in which multiple wires are used to forma conductor channel, in accordance with one embodiment of the presentinvention;

FIG. 2B shows a variation of the layout of FIG. 2A in which a horizontalposition of the RICAs is reversed, in accordance with one embodiment ofthe present invention;

FIG. 3 shows an example layout in which multiple 3-wire conductorchannels are interleaved and connected through a pair of overlappingRICAs, in accordance with one embodiment of the present invention;

FIG. 4 shows an example layout in which three 2-wire conductor channelsare routed horizontally to connect with three 2-wire conductor channelsthat are routed vertically, in accordance with one embodiment of thepresent invention;

FIG. 5 shows an example layout in which a single-wire routing is definedwithin a multi-wire conductor channel, in accordance with one embodimentof the present invention;

FIG. 6 shows an example layout in which RICAs are used to connect twointerleaved 3-wire conductor channels with two interleaved 2-wireconductor channels, in accordance with one embodiment of the presentinvention;

FIG. 7 shows an interlevel connector pattern used to connectnon-interleaved horizontal and vertical multi-wire conductor channels,in accordance with one embodiment of the present invention;

FIG. 8 shows an example layout in which a non-interleaved conductorchannel is embedded within another conductor channel, in accordance withone embodiment of the present invention;

FIG. 9A shows an example of Opportunistic Strapping (OSt), in accordancewith one embodiment of the present invention;

FIG. 9B shows an example layout in which a non-redundant RICA is used toconnect multiple horizontal conductor channels to multiple verticalconductor channels, in accordance with one embodiment of the presentinvention;

FIG. 10 shows an example routing between multiple locations in a chiplayout, in accordance with one embodiment of the present invention;

FIG. 11 shows an example layout in which OSt strap wires are used withnon-interleaved conductor channels, in accordance with one embodiment ofthe present invention;

FIG. 12A shows use of supplemental OSt strap wires in a dense interlevelconnector pattern without orthogonally adjacent interlevel connectorplacement, in accordance with one embodiment of the present invention;

FIG. 12B shows a variation of the example layout of FIG. 12A in whichOSt strap wires are used to connect adjacent and commonly orientedwires, in accordance with one embodiment of the present invention;

FIG. 12C shows a variation of the example layout of FIG. 12A in whicheach wire of a given conductor channel is connect by a single OSt strapwire, in accordance with one embodiment of the present invention;

FIG. 13A shows an example layout in which an unused fill wire isincorporated into a conductor channel by way of OSt strap wires, inaccordance with one embodiment of the present invention;

FIG. 13B shows the example layout of FIG. 13A with a shorter length fillwire, in accordance with one embodiment of the present invention;

FIG. 14A shows an example layout demonstrating how OSt strap wires canconnect to fill wires at any point along the length of the fill wires,in accordance with one embodiment of the present invention;

FIG. 14B shows an example layout demonstrating how shorter segments offill wires may be connected to conductor channel wires, in accordancewith one embodiment of the present invention;

FIG. 14C shows an example layout demonstrating how tuning wires can beused to increase the capacitance on a channel wire or other wire, or toincrease interlevel connector density in an area, in accordance with oneembodiment of the present invention;

FIG. 15 shows an exemplary chip level layout based on the dynamic arrayarchitecture, in accordance with one embodiment of the presentinvention;

FIG. 16 shows a flowchart of a method for defining a RICA in asemiconductor chip layout, in accordance with one embodiment of thepresent invention; and

FIG. 17 shows a flowchart of a method for wire routing in asemiconductor chip layout, in accordance with one embodiment of thepresent invention.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be apparent, however, to one skilled in the art that the presentinvention may be practiced without some or all of these specificdetails. In other instances, well known process operations have not beendescribed in detail in order not to unnecessarily obscure the presentinvention.

Dynamic Array Architecture

In deep sub-micron VLSI (Very-Large-Scale Integration) design, processcompensation techniques (PCTs) such as Optical Proximity Correction(OPC) or sub-resolution feature utilization, among others, enhance theprinting of layout features. PCTs are easier to develop and implementwhen the layout is highly regular and when the quantity and diversity oflithographic interactions are minimized across the layout.

The dynamic array architecture represents a semiconductor device designparadigm capable of enhancing PCT development and implementation. In thedynamic array architecture, linear-shaped layout features are definedalong a regular-spaced virtual grate (or regular-spaced virtual grid) ina number of levels of a cell, i.e., in a number of levels of asemiconductor chip. The virtual grate is defined by a set of equallyspaced, parallel virtual lines extending across a given level in a givenchip area. The virtual grid is defined by a first set of equally spaced,parallel virtual lines extending across a given level in a given chiparea in a first direction, and by a second set of equally spaced,parallel virtual lines extending across the given level in the givenchip area in a second direction, where the second direction isperpendicular to the first direction. In various embodiments, thevirtual grate of a given level can be oriented either substantiallyperpendicular of substantially parallel to the virtual grate of anadjacent level.

A linear layout feature is defined as a layout shape that extends alonga virtual line of a virtual grate without contacting a neighboringlinear layout feature that extends along a different virtual line of thevirtual grate. In one embodiment, a linear layout feature can be definedto have a substantially rectangular cross-section when viewed in anas-drawn state. In another embodiment, a linear layout feature can bedefined to have a primarily rectangular cross-section defined by a widthand length, with some allowable variation in width along its length. Itshould be understood, however, that in this embodiment, the linearlayout feature of varying width may not contact a neighboring linearlayout feature that extends along a different virtual line of the samevirtual grate within the same chip level. For example, some linearlayout features may have one or more variations in width at any numberof locations along their length, wherein “width” is defined across thesubstrate in a direction perpendicular to the virtual line along whichthe linear layout feature is disposed. Such a variation in width may beused to define a contact head upon which a contact is to connect, or mayserve some other purpose. Additionally, different linear layout featureswithin a given chip level can be defined to have the same width ordifferent widths, so long as the width variation is predictable from amanufacturing perspective and does not adversely impact the manufactureof the linear layout feature or its neighboring layout features.

In the dynamic array architecture, variations in a verticalcross-section shape of an as-fabricated linear layout feature can betolerated to an extent, so long as the variation in the verticalcross-section shape is predictable from a manufacturing perspective anddoes not adversely impact the manufacture of the given linear layoutfeature or its neighboring layout features. In this regard, the verticalcross-section shape corresponds to a cut of the as-fabricated linearlayout feature in a plane perpendicular to the centerline of the linearlayout feature.

FIG. 15 shows an exemplary chip level layout based on the dynamic arrayarchitecture, in accordance with one embodiment of the presentinvention. A number of virtual lines 1501, 1503, 1505, 1507, 1509 areeach defined to extend across the substrate, i.e., across the chip levellayout of the portion of the chip, in a single common direction (ydirection). Each of linear layout features 1511, 1513, 1515, 1517, 1519,1521 is defined to extend along a single virtual line (1501, 1503, 1505,1505, 1507, 1509, respectively), without contacting a neighboring linearlayout feature that extends along a different virtual grate line. Somelinear layout features, such as 1511, 1515, 1517, 1521, are defined tohave a substantially rectangular cross-section when viewed in theiras-drawn state. Whereas other linear layout features, such as 1513 and1519, are defined to have some variation in width (in x direction) alongtheir length (in y direction). It should be appreciated that althoughlinear layout features 1513 and 1519 vary in width along their length,neither of linear layout features 1513 and 1519 contacts a neighboringlinear layout feature that extends along a different virtual grate line.

In one embodiment, each linear layout feature of a given chip level issubstantially centered upon one of the virtual lines of the virtualgrate associated with the given chip level. A linear layout feature isconsidered to be substantially centered upon a particular virtual grateline when a deviation in alignment between of the centerline of thelinear layout feature and the particular virtual grate line issufficiently small so as to not reduce a manufacturing process windowfrom what would be achievable with a true alignment between of thecenterline of the linear layout feature and the virtual grate line. Inone embodiment, the above-mentioned manufacturing process window isdefined by a lithographic domain of focus and exposure that yields anacceptable fidelity of the layout feature. In one embodiment, thefidelity of a layout feature is defined by a characteristic dimension ofthe layout feature.

In another embodiment, some linear layout features in a given chip levelmay not be centered upon a virtual grate line. However, in thisembodiment, the linear layout features remain parallel to the virtuallines of the virtual grate, and hence parallel to the other linearlayout features in the given chip level. Therefore, it should beunderstood that the various linear layout features defined in a layoutof a given chip level are oriented to extend across the given chip levelin a parallel manner.

In one embodiment, within a given chip level defined according to thedynamic array architecture, proximate ends of adjacent, co-alignedlinear layout features may be separated from each other by asubstantially uniform gap. More specifically, adjacent ends of linearlayout features defined along a common virtual grate line are separatedby an end gap, and such end gaps within the chip level associated withthe virtual grate may be defined to span a substantially uniformdistance. Additionally, in one embodiment, a size of the end gaps isminimized within a manufacturing process capability so as to optimizefilling of a given chip level with linear layout features.

Also, in the dynamic array architecture, a portion of a chip level canbe defined to have any number of virtual grate lines occupied by anynumber of linear layout features. In one example, a portion of a givenchip level can be defined such that all lines of its virtual grate areoccupied by at least one linear layout feature. In another example, aportion of a given chip level can be defined such that some lines of itsvirtual grate are occupied by at least one linear layout feature, andother lines of its virtual grate are vacant, i.e., not occupied by anylinear layout features. Furthermore, in a portion of a given chip level,any number of successively adjacent virtual grate lines can be leftvacant. Also, the occupancy versus vacancy of virtual grate lines bylinear layout features in a portion of a given chip level may be definedaccording to a pattern or repeating pattern across the given chip level.

In a given chip level, some of the linear layout features may formfunctional structures within an integrated circuit, and other linearlayout features may be non-functional with respect to integrated circuitoperation. It should be understood that the each of the linear layoutfeatures, regardless of function, is defined to extend across the chiplevel in the common direction of the virtual grate and to be devoid of asubstantial change in direction along its length. It should beunderstood that each of the linear layout features, regardless offunction, is defined such that no linear layout feature along a givenvirtual grate line is configured to connect directly within the samechip level to another linear layout feature defined along a differentvirtual grate line.

Additionally, within the dynamic array architecture, vias and contactsare defined to interconnect a number of layout features in variouslevels so as to form a number of functional electronic devices, e.g.,transistors, and electronic circuits. Layout features for the vias andcontacts can be aligned to a virtual grid. In one embodiment, a virtualgrid is defined as a combination of virtual grates associated with aplurality of levels to which the vias and contacts will connect. Also,in one embodiment, a combination of virtual grates used to define avirtual grid can include one or more virtual grates defined independentfrom a particular chip level.

In the dynamic array architecture, a number of layout features invarious chip levels form functional components of an electronic circuit.Additionally, some of layout features within various chip levels may benon-functional with respect to an electronic circuit, but aremanufactured nonetheless so as to reinforce manufacturing of neighboringlayout features. It should be understood that the dynamic arrayarchitecture is defined to enable accurate prediction of semiconductordevice manufacturability with a high probability.

In view of the foregoing, it should be understood that the dynamic arrayarchitecture is defined by placement of linear layout features on aregular-spaced grate (or regular-spaced grid) in a number of levels of acell, such that the linear layout features in a given level of the cellare oriented to be substantially parallel with each other in theirtraversal direction across the cell. As discussed above, in the dynamicarray architecture, each as-drawn linear layout feature, i.e., prior toPCT processing, is defined to be devoid of a substantial change indirection relative to its traversal direction across the cell.

Cell

A cell, as referenced herein, represents an abstraction of a logicfunction, and encapsulates lower-level integrated circuit layouts forimplementing the logic function. It should be understood that a givenlogic function can be represented by multiple cell variations, whereinthe cell variations may be differentiated by feature size, performance,and process compensation technique (PCT) processing. For example,multiple cell variations for a given logic function may bedifferentiated by power consumption, signal timing, current leakage,chip area, OPC, RET, etc. It should also be understood that each celldescription includes the layouts for the cell in each level of a chip,as required to implement the logic function of the cell. Morespecifically, a cell description includes layouts for the cell in eachlevel of the chip extending from the substrate level up through aparticular interconnect level.

Exemplary Embodiments

When routing conductors in a restricted architecture, such as thedynamic array architecture, multi-wire buses and multi-wire channels maybe required. Various embodiments are disclosed herein for providingmulti-wire buses and multi-wire channels that are connected usinginterlevel connectors, such as vias and contacts, which are placedaccording to a virtual grid. In one embodiment, interconnect chip levelfeatures, i.e., wires, in a given interconnect chip level are placedaccording to a virtual grate that is spatially related to the virtualgrid for interlevel connector placement. As used herein the term wirerefers to an electrically conductive structure defined within a level ofa semiconductor chip. By way of example, wires may be formed of metal,polysilicon, or essentially any other electrically conductive materialused in the manufacture of semiconductor chips. Also, in one embodiment,a wire can be defined by a local interconnect structure formed throughdoping and/or salicide processes.

FIG. 1A is an illustration showing placement of wires and interlevelconnectors, in accordance with one embodiment of the present invention.Wires within a given chip level are centered on virtual lines of avirtual grate associated with the given chip level. In one embodiment,adjacent virtual lines within a given virtual grate are separated by asubstantially uniform pitch. Vertically oriented wires 801 c and 801 dare placed in one interconnect chip level according to the virtual gratethat includes virtual lines 803 a, 803 b, 803 c. Horizontally orientedwires 801 a and 801 b are placed in another interconnect chip levelaccording to the virtual grate that includes virtual lines 803 d, 803 e,803 f. As used herein, the term “vertical” refers to the Y-axisdirection, and the term “horizontal” refers to the X-axis direction,wherein the X-Y plane is oriented substantially parallel to theunderlying substrate of the chip. Additionally, as used herein, the terminterlevel connector refers to an electrically conductive structuredefined to extend between any two different chip levels to electricallyconnect a structure in one chip level to a structure in another chiplevel. Examples of interlevel connectors include without limitationvias, gate contacts, and diffusion contacts.

Interlevel connectors can be placed according to a virtual grid, whereinthe virtual grid is defined by two perpendicularly oriented virtualgrates. In one embodiment, the two perpendicularly oriented virtualgrates of the virtual grid can be defined for two separate levels, e.g.,for two separate interconnect chip levels in the case of vias, or for agate chip level and an interconnect chip level in the case of gatecontacts. In this embodiment, the virtual grates for the differentlevels may or may not have a specification dependency upon each other.Valid interlevel connector placement locations may be defined in anumber of ways, including but not limited to, intersection pointsbetween virtual lines within a virtual grid, i.e., gridpoints in thevirtual grid.

The perpendicular distance between parallel and adjacent virtual linesin a virtual grid is referred to as a virtual grid pitch, and may bedetermined in a number of ways. For example, the virtual grid pitch maybe equal to a minimum wire, i.e., conductive feature, width plus aminimum wire-to-wire space. Also, the virtual grid pitch betweenadjacent vertically oriented virtual lines can be different from thevirtual grid pitch between adjacent horizontally oriented virtual lines.Thus, a virtual grid for interlevel connector placement can includevirtual grates associated with two different chip levels, wherein eachof the virtual grates is defined by a different pitch.

FIG. 1A depicts a Rectangular Interlevel Connector Array (RICA) 805defined by the two horizontal wires (801 a and 801 b), the two verticalwires (801 c and 801 d), and the interlevel connectors (802 a, 802 b,802 c, 802 d) which connect them. It should be understood that the wires801 a-801 d of FIG. 1A can represent any type of wire on any chip level.For example, wires 801 c and 801 d may represent conductive features ofa gate chip level, and wires 801 a and 801 b may represent conductivefeatures of a first interconnect chip level. In another example, wires801 c and 801 d may represent conductive features of one interconnectchip level, and wires 801 a and 801 b may represent conductive featuresof another interconnect chip level. Also, in various embodiments,interlevel connectors 802 a-802 d can represent either vias or contacts,depending on the chip level and functionality of the wires 801 a-801 dto which they connect. It should be appreciated that in the embodimentof FIG. 1A, wires 801 a and 801 b are placed on virtual grate lines 803d and 803 f, respectively. Similarly, wires 801 c and 801 d are placedon virtual grate lines 803 a and 803 c, respectively. Although theembodiment of FIG. 1A includes a vacant virtual grate line 803 b betweenwires 801 c and 801 d, and a vacant virtual grate line 803 e betweenwires 801 a and 801 b, in other embodiments, the virtual grate lines 803b and 803 e may be occupied by wires (related or non-related), dependingon wire spacing and wire width specifications/restrictions.

Each wire (801 a-801 d) may extend beyond an interlevel connector (802a-802 d) by a specified extension distance or may continue to otherrouting points beyond the RICA 805. For example, wire 801 a may bedefined to have either of horizontal extensions 804 a or 804 c. Wire 801b may be defined to have either of horizontal extensions 804 b or 804 d.Wire 801 c may be defined to have either of vertical extensions 804 e or804 g. Wire 801 d may be defined to have either of vertical extensions804 f or 804 h. Also, horizontal/vertical extensions of wires beyond aninterlevel connector may be defined in a related manner or may bedefined independently. Also, an extension distance of a given wirebeyond an interlevel connector location may be specified as necessary tosatisfy design or layout requirements. In one embodiment, a wire may bedefined to end essentially at an edge of an interlevel connector,thereby resulting in a substantially non-existent extension distance.Also, in one embodiment, a wire may be defined to partially traverse aninterlevel connector, thereby resulting in a negative extensiondistance.

At a given RICA location, a 90-degree elbow intersection, aT-intersection, or a cross intersection may be formed by linearconductive features, e.g., wires, on two or more different chip levels.An elbow intersection occurs where a first wire on one chip levelconnects with a second wire on another chip level by way of aninterlevel connector, and wherein each of the first and second wiresterminates at or just beyond the connection location defined by theinterlevel connector, and wherein the first and second wires extend in asubstantially perpendicular direction relative to each other. In oneembodiment of the elbow intersection, the first wire and/or second wiremay extend partially across the interlevel connector used to connect thefirst and second wires. In this embodiment, the wire that extendspartially across the interlevel connector is considered to have anegative extension distance with respect to the interlevel connector.

A T-intersection occurs where a first wire on one chip level connectswith a second wire on another chip level by way of an interlevelconnector, and wherein the first wire terminates at or just beyond theconnection location defined by the interlevel connector, and wherein thesecond wire continues substantially beyond the connection locationdefined by the interlevel connector, and wherein the first and secondwires extend in a substantially perpendicular direction relative to eachother. In one embodiment of the T-intersection, the first wire mayextend partially across the interlevel connector used to connect thefirst and second wires. In this embodiment, the first wire is consideredto have a negative extension distance with respect to the interlevelconnector. A cross intersection occurs where a first wire on one chiplevel connects with a second wire on another chip level by way of aninterlevel connector, and wherein both the first and second wirescontinue substantially beyond the connection location defined by theinterlevel connector, and wherein the first and second wires extend in asubstantially perpendicular direction relative to each other.

A virtual grid defined for interlevel connector placement may bespecified such that orthogonally adjacent interlevel connectorplacements are allowed in one or both of the horizontal and verticaldirections. In one embodiment, wires associated with an RICA may beplaced on adjacent virtual grate lines. FIG. 1B shows an example where ahorizontally oriented virtual grate (including virtual lines 813 d and813 e) of an interlevel connector placement virtual grid (includingvirtual lines 813 a-813 e) allows for placement of interlevel connectors(812 a/812 c and 812 b/812 d) on adjacent virtual lines (813 d and 813e). The interlevel connector 812 a provides for connection of wires 811a and 811 c defined on different chip levels. The interlevel connector812 b provides for connection of wires 811 a and 811 d defined ondifferent chip levels. The interlevel connector 812 c provides forconnection of wires 811 b and 811 c defined on different chip levels.The interlevel connector 812 d provides for connection of wires 811 band 811 d defined on different chip levels.

FIG. 1C shows an example where an interlevel connector placement virtualgrid (including virtual lines 823 a-823 d) allows for placement ofinterlevel connectors (822 a-822 d) on adjacent virtual lines in boththe horizontal and vertical directions. The interlevel connector 822 aprovides for connection of wires 821 a and 821 c defined on differentchip levels. The interlevel connector 822 b provides for connection ofwires 821 a and 821 d defined on different chip levels. The interlevelconnector 822 c provides for connection of wires 821 b and 821 c definedon different chip levels. The interlevel connector 822 d provides forconnection of wires 821 b and 821 d defined on different chip levels.

When designing in accordance with the dynamic array architecture orother restricted architecture, multiple wires may be used to replicatethe function of a single wire of larger width. FIG. 2A shows an examplelayout in which multiple wires are used to form a conductor channel,wherein the conductor channel is electrically equivalent to a singleconductor, i.e., single wire. Specifically, multiple wires 201 and 203form a first conductor channel A1. Multiple wires 202 and 204 form asecond conductor channel B1. Multiple wires 205 and 207 form a thirdconductor channel A2. Multiple wires 206 and 208 form a fourth conductorchannel B2. In one embodiment, each of the conductor channels A1, A2,B1, and B2 is defined to respectively replace a single larger wire. Itshould be understood that a given conductor channel may be defined byany number of wires greater than one. Also, it should be understood thatconductor channels defined within different chip levels can be connectedto each other by way of a RICA. A number of exemplary embodiments aredisclosed herein for RICA-connected conductor channels in which theconnected conductor channels extend in perpendicular directions withrespect to each other. However, it should be understood that in variousembodiments, RICA-connected conductor channels in different chip levelsmay extend in a common direction or in different directions.

In the example of FIG. 2A, RICA 209 is formed by interlevel connectors209 a-209 d to connect the horizontal conductor channel A1 to thevertical conductor channel A2, thereby associating both conductorchannels A1 and A2 with a common net A. Also, RICA 210 is formed byinterlevel connectors 210 a-210 d to connect the horizontal conductorchannel B1 to the vertical conductor channel B2, thereby associatingboth conductor channels B1 and B2 with a common net B. The RICAs 209 and210 are overlapped such that the interlevel connectors 209 a-209 d and210 a-210 d are placed in a non-adjacent manner. More specifically,interleaving of the conductor channel wires 201-208 enables overlappingof the RICAs 209 and 210 to connect the horizontal conductor channels A1and B1 to the vertical conductor channels A2 and B2, respectively,without either horizontally adjacent or vertically adjacent interlevelconnector placements within the RICAs 209, 210.

Overlapped RICAs with corresponding interleaved conductor channel wiresmay be utilized to avoid interlevel connector placements with acenter-line spacing that is equivalent to the center-line spacing ofwires on levels that connect to the interlevel connector underconsideration. For example, overlapped RICAs with correspondinginterleaved conductor channel wires may be used in a multi-wire bus toensure a separation of more than one wire pitch between interlevelconnector, or to avoid interlevel connector placements on vertically orhorizontally adjacent virtual grid lines. Placement of interlevelconnectors on vertically or horizontally adjacent virtual grid lines isreferred to herein as an orthogonally adjacent placement. Also, byinterleaving the wires of the different conductor channels, a denseinterlevel connector placement pattern can be obtained at theintersection of the vertically and horizontally oriented conductorchannels (A1/A2, B1/B2) without use of orthogonally adjacent interlevelconnector placements.

FIG. 2B shows a variation of the embodiment of FIG. 2A in which ahorizontal position of RICAs 209 and 210 is reversed. The horizontalposition reversal of RICAs 209 and 210 causes connected wires of theconnected conductor channels to maintain an inner-to-outer sequencethrough the RICAs 209 and 210. Specifically, innermost wire 204 ofconductor channel B1 is connected to innermost wire 206 of conductorchannel B2. Also, outermost wire 201 of conductor channel A1 isconnected to outermost wire 207 of conductor channel A2. By maintainingthe inner-to-outer conductor channel wire sequence at interlevelconnector locations within the RICA, an edge relationship betweenadjacent wires may be averaged over a run length of the conductorchannels. This technique can be employed with any number of conductorchannels and with any number of wires per conductor channel.

Overlapping RICAs can be extended to connect any number of conductorchannels and to accommodate any number of wires per conductor channel.FIG. 3 shows an example embodiment in which interleaved 3-wire conductorchannels are connected through a pair of overlapping RICAs 513 and 514.A first conductor channel A1 is formed by horizontal wires 501, 503, and505. A second conductor channel B1 is formed by horizontal wires 502,504, and 506. A third conductor channel A2 is formed by vertical wires508, 510, and 512. A fourth conductor channel B2 is formed by verticalwires 507, 509, and 511. It should be understood that horizontal wires501-506 are defined in a chip level separate from vertical wires507-512. The RICA 513 includes interlevel connectors defined to connecthorizontally oriented conductor channel A1 to vertically orientedconductor channel A2, thereby associating both conductor channels A1 andA2 with a net A. The RICA 514 includes interlevel connectors defined toconnect horizontally oriented conductor channel B1 to verticallyoriented conductor channel B2, thereby associating both conductorchannels B1 and B2 with a net B.

FIG. 4 shows an example embodiment in which three 2-wire conductorchannels (A1, B1, C1) are routed horizontally to connect with three2-wire conductor channels (A2, B2, C2) that are routed vertically.Specifically, conductor channel A1 (defined by wires 520 and 523) isrouted horizontally to connect with vertically routed conductor channelA2 (defined by wires 528 and 531) through RICA 534. Conductor channel B1(defined by wires 521 and 524) is routed horizontally to connect withvertically routed conductor channel B2 (defined by wires 527 and 530)through RICA 533. Conductor channel C1 (defined by wires 522 and 525) isrouted horizontally to connect with vertically routed conductor channelC2 (defined by wires 526 and 529) through RICA 532. In variousembodiments, the wires 520-525 of the horizontal conductor channels A1,B1, and C1 can be interleaved in different orders, with the wires of thevertical conductor channels A2, B2, and C2 correspondingly interleaved.However, in an embodiment in which the interlevel connector placementvirtual grid does not support orthogonally adjacent interlevel connectorplacement, the wires 520-525 of the horizontal conductor channels A1,B1, C1 should be arranged so as to avoid adjacent routing of multiplewires of the same conductor channel. Similarly, in this embodiment, thewires 526-531 of the vertical conductor channels A2, B2, C2 should bearranged so as to avoid adjacent routing of multiple wires of the sameconductor channel.

FIG. 5 shows an example embodiment in which a single-wire routing isdefined within a multi-wire conductor channel. Wires 551 and 553 definea horizontal conductor channel A1. Wires 554 and 556 define a verticalconductor channel A2. The horizontal and vertical conductor channels A1and A2 are connected together by a RICA 558 defined by interlevelconnectors 558 a. A single-wire routing net B is defined by a horizontalwire 552, connected through an interlevel connector 557 to a verticalwire 555. Because the single-wire routing interlevel connector 557 isplaced within the RICA 558, the single-wire routing wire 552 is placedwithin horizontal conductor channel A1, and the single-wire routing wire555 is placed within the vertical conductor channel A2. It should beunderstood that in various embodiments, the horizontal wire 552 and/orthe vertical wire 555 can be defined to extend beyond the interlevelconnector 557, and even beyond the RICA 558. Also, it should beappreciated that essentially any number of single-wire routings can beplaced within, i.e., interleaved with, one or more conductor channels.

RICAs may be used to connect two or more multi-wire conductor channelsthat have different numbers of wires per conductor channel. FIG. 6 showsan example embodiment in which RICAs 711 and 712 are used to connect twointerleaved 3-wire conductor channels (A1 and B1) with two interleaved2-wire conductor channels (A2 and B2). Horizontal conductor channel A1is defined by wires 701, 703, and 705. Horizontal conductor channel B1is defined by wires 702, 704, and 706. Vertical conductor channel A2 isdefined by wires 708 and 710. Vertical conductor channel B2 is definedby wires 707 and 709. RICA 711 includes interlevel connectors placed toconnect the horizontal conductor channel A1 with the vertical conductorchannel A2. Therefore, RICA 711 is defined to transition the 3-wirehorizontal conductor channel A1 into the 2-wire vertical conductorchannel A2, vice-versa. RICA 712 includes interlevel connectors placedto connect the horizontal conductor channel A2 with the verticalconductor channel B2. Therefore, RICA 712 is defined to transition the3-wire horizontal conductor channel B1 into the 2-wire verticalconductor channel B2, vice-versa. Also, the interleaving of theconductor channel A1 wires (701, 703, 705) with the conductor channel B1wires (702, 704, 706), and the interleaving of the conductor channel A2wires (708, 710) with the conductor channel B2 wires (707, 709) allowsthe interlevel connectors of RICAs 711 and 712 to be placed so as toavoid orthogonally adjacent interlevel connector placements.

If adjacent interlevel connector placements are allowed,non-interleaving interlevel connector patterns may be employed. FIG. 7shows an example of an interlevel connector pattern used to connectnon-interleaved horizontal and vertical multi-wire conductor channels. Ahorizontal conductor channel A1 defined by wires 241 and 242 isconnected through a RICA 249 to a vertical conductor channel A2 definedby wires 247 and 248. Also, a horizontal conductor channel B1 defined bywires 243 and 244 is connected through a RICA 250 to a verticalconductor channel B2 defined by wires 245 and 246. Because the conductorchannels A1 and B1 are non-interleaved, and because the conductorchannels B2 and A2 are non-interleaved, the RICAs 249 and 250 do notoverlap each other. Use of non-overlapping RICAs can be extended to anynumber of non-interleaved conductor channels, and to any number of wiresper non-interleaved conductor channel.

Additionally, a non-interleaved conductor channel can be embedded withinone or more other conductor channels, thereby causing one RICA to beembedded within another RICA. FIG. 8 shows an example layout in which anon-interleaved conductor channel is embedded within another conductorchannel. Specifically, a non-interleaved conductor channel B1 defined bywires 262 and 263 is connected through a RICA 269 to a conductor channelB2 defined by wires 266 and 267. Another conductor channel A1 defined bywires 261 and 264 is connected through a RICA 270 to a conductor channelA2 defined by wires 265 and 268. The horizontal conductor channel B1 isembedded within the horizontal conductor channel A1. Similarly, thevertical conductor channel B2 is embedded within the vertical conductorchannel A2. Therefore, the RICA 269 is embedded within the RICA 270.

If additional redundancy or interconnection is required, a techniquereferred to herein as Opportunistic Strapping (OSt) may be employed. Onemethod to perform OSt is to place and connect strap wires between memberwires of the same conductor channel, wherein the strap wires are routedperpendicularly to the routing direction of the conductor channel wiresto which they connect, and wherein the strap wires are defined on adifferent chip level than the conductor channel wires to which theyconnect. FIG. 9A shows an example of OSt. In FIG. 9A, RICA 309 connectshorizontal conductor channel A1 defined by wires 301 and 303 to verticalconductor channel A2 defined by wires 305 and 307. Also, RICA 310connects horizontal conductor channel B1 defined by wires 302 and 304 tovertical conductor channel B2 defined by wires 306 and 308. RICAs 309and 310 are reinforced by periodic strapping of the horizontal andvertical wires to which they connect. Specifically, RICA 309 isreinforced by vertical strap wire 311 and by horizontal strap wire 313.Similarly, RICA 310 is reinforced by vertical strap wire 312 and byhorizontal strap wire 314. It should be understood that OSt may includeuse of multiple commonly oriented strap wires to reinforce a given RICA.

OSt can also be used to add redundancy to a non-redundant RICA. FIG. 9Bshows an example embodiment in which a non-redundant RICA 329 is used toconnect a horizontal conductor channel A1 to a vertical conductorchannel A2, and to connect a horizontal conductor channel B1 to avertical conductor channel B2. While a non-redundant RICA, such as 329,provides no redundancy or interconnection between wires of a commonconductor channel, use of a non-redundant RICA may be more areaefficient in some layout instances. To compensate for the lack ofinterconnection and redundancy in a non-redundant RICA, strap wires canbe added down the horizontal and vertical run lengths of the conductorchannels entering the non-redundant RICA. For example, strap wire 330 isconnected between wires 321 and 323 of horizontal conductor channel A1.

Strap wire 331 is connected between wires 322 and 324 of horizontalconductor channel B1. Strap wire 332 is connected between wires 325 and327 of vertical conductor channel A2. Strap wire 333 is connectedbetween wires 326 and 328 of vertical conductor channel B2. Each ofstrap wires 330-333 reinforces the interlevel connections withinnon-redundant RICA 329.

In the OSt process, an extension of a strap wire beyond an interlevelconnector to which it is connected may or may not be related to anextension of a channel wire beyond an interlevel connector in a RICA.Also, the extension of strap wires beyond their associated interlevelconnectors may be specified globally or on per wire basis.

In the OSt process, strap wires can be distributed along an entirelength of a conductor channel segment. FIG. 10 shows an example routingbetween a location 400 and a location 406 in a chip layout. The routingdepicted in FIG. 10 includes five conductor channel segments 401, 402,403, 404, and 405. A number of strap wires can be placed along eachconductor channel segment 401-405. Based on the degree of additionalinterconnect, redundancy required, desired segment capacitance and theproximity of nearby fill wires, a minimum number of OSt strap wires maybe specified. In one embodiment, when local routing is completed,additional OSt strap wires are inserted in the layout as space permits.In one embodiment, a maximum number of OSt strap wires may be specifiedon a per route or per conductor channel segment basis.

If adjacent interlevel connectors are permitted by the virtual grid,non-interleaved conductor channels may employ OSt strap wires. FIG. 11shows an example layout in which OSt strap wires are used withnon-interleaved conductor channels. A strap wire 350 is used to connectwires 341 and 342 of horizontal conductor channel A1. A strap wire 351is used to connect wires 343 and 344 of horizontal conductor channel B1.A strap wire 352 is used to connect wires 345 and 346 of verticalconductor channel A2. A strap wire 353 is used to connect wires 347 and348 of vertical conductor channel B2. The OSt strap wires 350-353provide additional interconnect and redundancy to the interlevelconnectors within the non-redundant RICA 349.

A dense interlevel connector pattern without orthogonally adjacentinterlevel connector placement can be supplemented by OSt strap wires toconnect a multi-wire horizontal conductor channel to a multi-wirevertical conductor channel, when each of the horizontal and verticalconductor channels is defined by four or more wires, such as shown inFIG. 12A. RICA 609 connects wires 601 and 603 of horizontal conductorchannel A1 to wires 605 and 607 of vertical conductor channel A2. RICA610 connects wires 602 and 604 of horizontal conductor channel A1 towires 606 and 608 of vertical conductor channel A2. The RICAs 609 and610 do not connect all the wires of the horizontal conductor channel A1to all the wires of the vertical conductor channel A2. However, thestrap wires 615 and 616 supplement the connections made through theRICAs 609 and 610, such that each of the wires 601-604 of the horizontalconductor channel A1 is connected to each of the wires 605-608 of thevertical conductor channel A2. Additional OSt strap wires 611, 612, 613,and 614 can also be used to reinforce the connections made by RICAs 609and 610.

If orthogonally adjacent interlevel connector placement is permitted bythe virtual grid, some or all of the OSt strap wires may be placed toconnect adjacent and commonly oriented wires. FIG. 12B shows a variationof the example layout of FIG. 12A in which OSt strap wires are used toconnect adjacent and commonly oriented wires. Specifically, a strap wire635 is used to connect wires 602 and 603. Therefore, the combination ofstrap wires 611, 612, and 635 serves to connect the wires 601-604 ofconductor channel A1. A strap wire 633 is used to connect wires 605 and606. A strap wire 634 is used to connect wires 607 and 608. Therefore,the combination of strap wires 616, 633, and 634 serves to connect wires605-608 of conductor channel A2.

FIG. 12C shows a variation of the example layout of FIG. 12A in whicheach wire of a given conductor channel is connect by a single OSt strapwire. Specifically, a strap wire 651 is defined to connect each of thewires 601-604 of conductor channel A1. Also, a strap wire 652 is definedto connect each of the wires 605-608 of conductor channel A2. Each ofthe strap wires 651 and 652 reinforces the connections of both RICAs 609and 610.

If one or more unused fill wires is routed near or adjacent to aconductor channel, OSt strap wires may be used to incorporate the unusedfill wire into the conductor channel, as shown in the example of FIG.13A. Wires 361 and 363 of horizontal conductor channel A1 are connectedto unused fill wire 376 by OSt strap wires 371 and 372, respectively.Also, if the unused fill wire runs near or adjacent to a RICA to whichits channel-by-incorporation is connected, the unused fill wire may beincorporated into the RICA. For example, in FIG. 13A, the unused fillwire 376 is extended into RICA 369. Therefore, RICA 369 is configured toconnect conductor channel A1, as defined by wires 361, 363, and 376, toconductor channel A2 defined by wires 365 and 367. Incorporation of afill wire into a conductor channel may serve to increase redundancy oralter the capacitance on conductor channel. Additionally, incorporationof a fill wire into a conductor channel may be used to increase theinterlevel connector density in the areas around other interlevelconnectors on the conductor channel.

It should be understood that the length of the fill wire does not needto be equal to or greater than the conductor channel segment to beincorporated into the conductor channel segment. For example, FIG. 13Bshows the example layout of FIG. 13A with the fill wire 376 replaced bya shorter length fill wire 397. A fill wire may be partiallyincorporated into a RICA. For example, the fill wire 397 is partiallyincorporated into RICA 389.

Moreover, use of OSt strap wires to connect to nearby or adjacentconductor channel wires does not need to occur near a RICA. As shown inFIG. 14A, strap wires can be used to connect to fill wires at any pointalong the length of the fill wires. Fill wire 901 is connected toconductor channel wire 903 by OSt strap wires 905 and 907. Fill wire 904is connected to conductor channel wire 902 by OSt strap wires 906 and908. Again, OSt strap wire connection to fill wire can be used toincrease redundancy, capacitance or interlevel connector density. Also,shorter segments of fill wires may be connected to conductor channelwires as shown in FIG. 14B. Fill wires 911 and 914 have a shorter lengththan conductor channel wires 912 and 913. Fill wire 911 is connected toconductor channel wire 913 by OSt strap wires 915 and 917. Fill wire 914is connected to conductor channel wire 912 by OSt strap wires 916 and918. It should be understood that OSt strap wires can be used to connectconductor channel wires to fill wires of any length.

To increase the capacitance on a channel wire, or any single wire forthat matter, or to increase interlevel connector density in an area, oneor more tuning wires can be perpendicular connected along the run lengthof the subject wire, even in the case that these perpendicular tuningwires do not connect to an additional conductor channel or fill wire, asshown in FIG. 14C. For example, perpendicular tuning wires 922-925 areconnected to wire 921. The frequency of these perpendicular tuning wiresmay be specified on a per wire basis, within a local area or globally.The perpendicular tuning wires do not need to be equally spaced alongthe length of the subject wire to which they are connected. Also, aminimum and maximum length may be specified for each perpendiculartuning wire. Also, a total length of all perpendicular tuning wiresconnected to a subject wire may be specified. The extension of a givenperpendicular tuning wire beyond the interlevel connector to which it isconnected can be defined independently from the extension of otherperpendicular tuning wires, OSt wires, or channel wires.

Based on the foregoing, it should be understood that multiple RICAs canbe overlapped to maintain an inner-to-outer sequence of conductorchannel wires when a horizontal conductor channel transitions to avertical conductor channel, vice-versa. Also, a RICA can be expanded toroute any number of conductor channels. Also, a RICA can be expanded toconnect any number of wires per conductor channel. Moreover, horizontaland vertical conductor channels defined by different numbers of wirescan be connected through use of a RICA. Each extension of a wire withregard to an interlevel connector, e.g., via or contact, may be definedin a unique manner. Also, each extension of a wire may be defined aseither negative, substantially zero, or positive with respect to an edgeposition of an interlevel connector.

Also, as discussed above, OSt strap wires can be used with RICAs or withany other type of interlevel connector pattern. OSt strap wires can beplaced at essentially any location along the run length of a conductorchannel. In one embodiment, OSt strap wires can be used to connect allwires in a multi-wire conductor channel. Also, in one embodiment, OStstrap wires can be used to connect to nearby fill wires.

FIG. 16 shows a flowchart of a method for defining a RICA in asemiconductor chip layout, in accordance with one embodiment of thepresent invention. The method includes an operation 1601 for defining avirtual grid for interlevel connector placement.

The virtual grid is defined by a first set of parallel virtual linesthat extend across the layout in a first direction, and by a second setof parallel virtual lines that extend across the layout in a seconddirection that is perpendicular to the first direction. Eachintersection point between the first and second sets of parallel virtuallines is a gridpoint in the virtual grid.

The method also includes an operation 1603 for placing a first pluralityof interlevel connector structures at respective gridpoints in thevirtual grid to form a first RICA. In various embodiments, eachinterlevel connector structure is defined as either a via structure or acontact structure. Neighboring interlevel connector structures of thefirst RICA are spaced apart from each other by a first number ofgridpoints in the first direction and by a second number of gridpointsin the second direction. Also, the first plurality of interlevelconnector structures of the first RICA are placed to collaborativelyconnect a first conductor channel in a first chip level with a secondconductor channel in a second chip level. The first conductor channel isdefined by a first plurality of wires which are electrically equivalentto a single conductor. The second conductor channel is defined by asecond plurality of wires which are electrically equivalent to a singleconductor.

In one embodiment, the first plurality of wires of the first conductorchannel are defined as parallel wires that extend in the first directionin the first chip level, and the second plurality of wires of the secondconductor channel are defined as parallel wires that extend in thesecond direction in the second chip level, such that the first andsecond conductor channels are perpendicular to each other. In anotherembodiment, the first plurality of wires of the first conductor channelare defined as parallel wires that extend in the first direction in thefirst chip level, and the second plurality of wires of the secondconductor channel are defined as parallel wires that also extend in thefirst direction in the second chip level, such that the first and secondconductor channels extend in the same direction.

In one embodiment, the spacing between neighboring interlevel connectorsis equal to one gridpoint of the virtual grid in the first direction,and one gridpoint of the virtual grid in the second direction. Inanother embodiment, the spacing between neighboring interlevelconnectors is equal to one gridpoint of the virtual grid in the firstdirection, and at least two gridpoints of the virtual grid in the seconddirection. In yet another embodiment, the spacing between neighboringinterlevel connectors is equal to at least two gridpoints in each of thefirst and second directions.

In one embodiment in which the interlevel connectors of the first RICAare spaced apart by at least two gridpoints of the virtual grid in eachof the first and second directions, a non-RICA interlevel connectorstructure is placed at a gridpoint within the first RICA, so as toconnect a first single wire with a second single wire. The first andsecond single wires are respectively defined in any different two levelsof the chip. Each of the first and second single wires is not part ofeither the first or second conductor channel.

In one embodiment, the method includes an operation for placing a secondplurality of interlevel connector structures at respective gridpoints inthe virtual grid to form a second RICA that is interleaved with thefirst RICA. In this embodiment, the interlevel connector structures ofthe second RICA are placed to collaboratively connect a third conductorchannel with a fourth conductor channel. The third and fourth conductorchannels are respectively defined in any different two levels of thechip. In one version of this embodiment, the interlevel connectors ofthe first RICA are spaced apart by at least two gridpoints of thevirtual grid in each of the first and second directions, and some of thesecond plurality of interlevel connector structures of the second RICAare placed at respective gridpoints between some of the first pluralityof interlevel connector structures of the first RICA.

In one embodiment, the method includes an operation for placing a secondplurality of interlevel connector structures at respective gridpoints inthe virtual grid to form a second RICA that is embedded within the firstRICA. Also in this embodiment, the interlevel connector structures ofthe second RICA are placed to collaboratively connect a third conductorchannel with a fourth conductor channel. The third and fourth conductorchannels are respectively defined in any different two levels of thechip. In this embodiment, the interlevel connectors of the first RICAare sufficiently spaced apart such that the first plurality ofinterlevel connector structures of the first RICA brackets the secondplurality of interlevel connector structures of the second RICA in boththe first and second directions.

In one embodiment, the method of FIG. 16 can optionally include anoperation for defining a first number of strap wires to electricallyconnect some of the first plurality of wires of the first conductorchannel together at a location outside the first RICA. Each of the firstnumber of strap wires is defined in any level of the chip other than thefirst level, and each of the first number of strap wires is orientedperpendicular to the first plurality of wires of the first conductorchannel. Each connection between the first number of strap wires and thefirst plurality of wires of the first conductor channel is formed by aninterlevel connector structure.

Additionally, in this embodiment, another operation can be optionallyperformed to define a second number of strap wires to electricallyconnect some of the second plurality of wires of the second conductorchannel together at a location outside the first RICA. Each of thesecond number of strap wires is defined in any level of the chip otherthan the second level, and each of the second number of strap wires isoriented perpendicular to the second plurality of wires of the secondconductor channel. Also, each connection between the second number ofstrap wires and the second plurality of wires of the second conductorchannel is formed by an interlevel connector structure.

FIG. 17 shows a flowchart of a method for wire routing in asemiconductor chip layout, in accordance with one embodiment of thepresent invention. The method includes an operation 1701 for defining afirst conductor channel layout in a first chip level. The firstconductor channel layout includes a first plurality of parallel wirelayout shapes having a common electrical connectivity and oriented in afirst direction. The method also includes an operation 1703 for defininga second conductor channel layout in a second chip level. The secondconductor channel layout includes a second plurality of parallel wirelayout shapes having a common electrical connectivity and oriented in asecond direction that is perpendicular to the first direction. The firstand second conductor channel layouts extend across each other within thechip layout at a crossing location.

The method further includes an operation 1705 for defining a first RICAlayout at the crossing location to connect the first conductor channellayout to the second conductor channel layout. The first RICA layoutincludes a first plurality of interlevel connector layout shapes placedto collaboratively connect the wire layout shapes of the first conductorchannel layout to the wire layout shapes of the second conductor channellayout. In one embodiment, the operation 1705 includes placing the firstplurality of interlevel connector layout shapes at respective gridpointsin a virtual grid for interlevel connector placement. The virtual gridis defined by a first set of parallel virtual lines that extend acrossthe chip layout in the first direction and by a second set of parallelvirtual lines that extend across the chip layout in the seconddirection. Each intersection point between the first and second sets ofparallel virtual lines is a gridpoint in the virtual grid for interlevelconnector placement.

It should be understood that the methods as described herein and theresulting cell layouts can be stored in a tangible form, such as in adigital format on a computer readable medium. Also, the inventiondescribed herein can be embodied as computer readable code on a computerreadable medium. The computer readable medium is any data storage devicethat can store data which can thereafter be read by a computer system.Examples of the computer readable medium include hard drives, networkattached storage (NAS), read-only memory, random-access memory, CD-ROMs,CD-Rs, CD-RWs, magnetic tapes, and other optical and non-optical datastorage devices. The computer readable medium can also be distributedover a network of coupled computer systems so that the computer readablecode is stored and executed in a distributed fashion.

Any of the operations described herein that form part of the inventionare useful machine operations. The invention also relates to a device oran apparatus for performing these operations. The apparatus may bespecially constructed for the required purpose, such as a specialpurpose computer. When defined as a special purpose computer, thecomputer can also perform other processing, program execution orroutines that are not part of the special purpose, while still beingcapable of operating for the special purpose. Alternatively, theoperations may be processed by a general purpose computer selectivelyactivated or configured by one or more computer programs stored in thecomputer memory, cache, or obtained over a network. When data isobtained over a network the data maybe processed by other computers onthe network, e.g., a cloud of computing resources.

The embodiments of the present invention can also be defined as amachine that transforms data from one state to another state. The datamay represent an article, that can be represented as an electronicsignal and electronically manipulate data. The transformed data can, insome cases, be visually depicted on a display, representing the physicalobject that results from the transformation of data. The transformeddata can be saved to storage generally, or in particular formats thatenable the construction or depiction of a physical and tangible object.In some embodiments, the manipulation can be performed by a processor.In such an example, the processor thus transforms the data from onething to another. Still further, the methods can be processed by one ormore machines or processors that can be connected over a network. Eachmachine can transform data from one state or thing to another, and canalso process data, save data to storage, transmit data over a network,display the result, or communicate the result to another machine.

While this invention has been described in terms of several embodiments,it will be appreciated that those skilled in the art upon reading thepreceding specifications and studying the drawings will realize variousalterations, additions, permutations and equivalents thereof. Therefore,it is intended that the present invention includes all such alterations,additions, permutations, and equivalents as fall within the true spiritand scope of the invention.

What is claimed is:
 1. A semiconductor chip, comprising: a firstconductor including a portion extending in a first direction, the firstconductor located within a first level of the semiconductor chip; asecond conductor including a portion extending in the first direction,the second conductor located within the first level of the semiconductorchip; a third conductor including a portion extending in the firstdirection, the third conductor located within the first level of thesemiconductor chip, the portion of the second conductor positionedbetween the portions of the first and third conductors in a seconddirection perpendicular to the first direction; a fourth conductorincluding a portion extending in the first direction, the fourthconductor located within the first level of the semiconductor chip, theportion of the third conductor positioned between the portions of thesecond and fourth conductors in the second direction; a fifth conductorincluding a portion extending in the second direction, the fifthconductor located within a second level of the semiconductor chip, theportion of the fifth conductor extending over the portions of the first,second, third, and fourth conductors; a first interlevel conductorcontacting the portion of the first conductor and contacting the portionof the fifth conductor; and a second interlevel conductor contacting theportion of the fourth conductor and contacting the portion of the fifthconductor.
 2. The semiconductor chip as recited in claim 1, wherein theportions of the first and fourth conductors form part of a firstelectrical node, and wherein the portions of the second and thirdconductors form part of a second electrical node.
 3. The semiconductorchip as recited in claim 1, wherein the first conductor islinear-shaped, and wherein the second conductor is linear-shaped, andwherein the third conductor is linear-shaped, and wherein the fourthconductor is linear-shaped.
 4. The semiconductor chip as recited inclaim 3, wherein the portion of the fifth conductor is linear-shaped. 5.The semiconductor chip as recited in claim 1, further comprising: asixth conductor including a portion extending in the second direction,the sixth conductor located within the second level of the semiconductorchip, the portion of the sixth conductor extending over the portions ofthe first, second, and third conductors; a third interlevel conductorcontacting the portion of the second conductor and contacting theportion of the sixth conductor; and a fourth interlevel conductorcontacting the portion of the third conductor and contacting the portionof the sixth conductor.
 6. The semiconductor chip as recited in claim 5,further comprising: a seventh conductor including a portion extending inthe second direction, the seventh conductor located within the secondlevel of the semiconductor chip, the portion of the seventh conductorextending over the portions of the first, second, and third conductors;a fifth interlevel conductor contacting the portion of the secondconductor and contacting the portion of the seventh conductor; and asixth interlevel conductor contacting the portion of the third conductorand contacting the portion of the seventh conductor.
 7. Thesemiconductor chip as recited in claim 6, wherein the portions of thesixth and seventh conductors are positioned next to each other.
 8. Thesemiconductor chip as recited in claim 6, further comprising: an eighthconductor including a portion extending in the second direction, theeighth conductor located within the second level of the semiconductorchip, the portion of the eighth conductor extending over the portions ofthe first and fourth conductors; a seventh interlevel conductorcontacting the portion of the first conductor and contacting the portionof the eighth conductor; and an eighth interlevel conductor contactingthe portion of the fourth conductor and contacting the portion of theeighth conductor.
 9. The semiconductor chip as recited in claim 8,wherein the portions of the sixth and seventh conductors are positionedbetween the portions of the fifth and eighth conductors in the firstdirection.
 10. The semiconductor chip as recited in claim 8, wherein thethird, fourth, fifth, and sixth interlevel conductors are positionedbetween the portions of the fifth and eighth conductors in the firstdirection and between the portions of the first and fourth conductors inthe second direction.
 11. The semiconductor chip as recited in claim 10,wherein the portions of the first, second, third, and fourth conductorsare positioned in accordance with a first uniform pitch as measured inthe second direction.
 12. The semiconductor chip as recited in claim 11,wherein the first conductor is linear-shaped, and wherein the secondconductor is linear-shaped, and wherein the third conductor islinear-shaped, and wherein the fourth conductor is linear-shaped. 13.The semiconductor chip as recited in claim 11, wherein the portions ofthe fifth, sixth, seventh, and eighth conductors are positioned inaccordance with a second uniform pitch as measured in the firstdirection.
 14. The semiconductor chip as recited in claim 13, whereinthe first conductor is linear-shaped, and wherein the second conductoris linear-shaped, and wherein the third conductor is linear-shaped, andwherein the fourth conductor is linear-shaped, and wherein the fifthconductor is linear-shaped, and wherein the sixth conductor islinear-shaped, and wherein the seventh conductor is linear-shaped, andwherein the eighth conductor is linear-shaped.
 15. The semiconductorchip as recited in claim 13, wherein the first and second uniformpitches are equal.